I'd say there are far more effective models to attack than multiple underground line cuts. If it were me, I would find a microwave relay site or two and take them out. They are usually remote, not well monitored if at all, and handle a huge amount of traffic.
_________________________
The ultimate result of shielding men from the effects of folly is to fill the world with fools.
-- Herbert Spencer, English Philosopher (1820-1903)